mac_get_lower_mac_handle
mh = mac_get_lower_mac_handle(mh);
(mac_get_lower_mac_handle((mac_handle_t)mip) != NULL))) {
mip = (mac_impl_t *)mac_get_lower_mac_handle((mac_handle_t)mip);
extern mac_handle_t mac_get_lower_mac_handle(mac_handle_t);